Define nitrogen estimation - kjeldahl''s method, Biology

Assignment Help:

Define Nitrogen Estimation - Kjeldahl's Method?

Nitrogen in the protein is estimated by a method referred to as Kjeldahl's method. Although over a period of time many other methods have emerged for determination of organic nitrogen, this method still remains an old favourite because it is reliable and has very well standardized procedures. The method involves the digestion of the weighed sample with concentrated sulphuric acid, selenium oxide, potassuim sulphate and copper sulphate in a long necked special digestion flask known as kjeldahl's flask. Potassium sulphate increases the boiling point of the mixture. Since the digestion results in fuming of the sulphuric acid, the procedure has to be carried out in a fume hood and the procedure takes several hours. The sample is digested until the solution in the digestion flask becomes clear after which it is transferred to an appropriate volumetric flask (usually 50 or 100 ml flask) and the volume is made up to the mark with distilled water. Aliquots of this sample are used for distillation in the kjeldahl's apparatus and nitrogen in the protein is estimated. Most proteins contains 16% nitrogen. Thus, percent nitrogen content is multiplied by 6.25 to get crude protein content.

1805_Nitrogen Estimation - Kjeldahl’s Method.png

The experiment involves decomposition of ammonium sulphate by a fixed volume of alkali (NaOH). Ammonium sulphate on decomposition releases ammonia which is collected in a flask of boric acid solution Tashiro's indicator. With boric acid ammonia forms a complex 'ammoium borate'. As ammonia is distilled into the boric acid, the Tashiro indicator slowly changes colour from pink to green. This is because the colour of the indicator is pH dependent - it is pink in acidic medium and green in alkaline medium. When the green coloured solution containing the boric-acid-ammonia complex is retitrated against H2SO4, the solution slowly becomes acidic again and the indicator becomes pink. This point when colour changes from green to pink is taken as the end point.


Related Discussions:- Define nitrogen estimation - kjeldahl''s method

Knotted network of capillaries, A knotted network of capillaries within a n...

A knotted network of capillaries within a nephron, the glomerulus, receives arterial blood and is porous enough to allow much of the fluid portion of the blood to flow out of it al

Explain a prosthetic considerations, Prosthetic Considerations The comp...

Prosthetic Considerations The complete aesthetic diagnosis of the patient should be done prior to implant placement in the aesthetic zone. The smile line of the patient is crit

Body cavity and coelom - metazoa, Body Cavity and Coelom - Metazoa Vac...

Body Cavity and Coelom - Metazoa Vacuoles, spaces, lacunae and cavities have been of importance in all organisms, may it a be plant or animal. All animals have cavities. The c

Limerick, how do we write a limerick spell?

how do we write a limerick spell?

Energy requirement during congestive cardiac failure, Q. Energy requirement...

Q. Energy requirement during congestive cardiac failure? Energy: Composition of the calorie requirements on the basis of body weight is usually not feasible due to the presence

Explain the eligibility of cardiac rehabilitation, Explain the eligibility ...

Explain the eligibility of Cardiac rehabilitation ? Cardiac rehabilitation services are prescribed for patients who: 1) Have had a myocardial infarction. 2) Have had coronary b

Write the meaning of dsme, Q. Write the meaning of DSME? Generally, it ...

Q. Write the meaning of DSME? Generally, it is observed that soon after being diagnosed with diabetes, the patient gets worried or get depressed. This is a stage where the pati

What is anabolism, Q. What is Anabolism? Anabolism Anabolism is a pr...

Q. What is Anabolism? Anabolism Anabolism is a process of synthesis or making of larger or complex molecules from smaller molecules. These molecules are of different kinds l

What is temperate grasslands, What is Temperate Grasslands? Grasslands ...

What is Temperate Grasslands? Grasslands are known by their common names in different regions of the world, such as the plains or prairies in North America, the steppe in Asia,

Agro industrial-fruit and vegetable factory by-products, FRUIT AND VEGETABL...

FRUIT AND VEGETABLE FACTORY BY-PRODUCTS India is emerging as a major producer of fruits and vegetables in the world. The country produced about 50 Mt of fruits and 90 Mt of veg

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd